McHank

Bought a Cherokee (-96 4.0, 2wd 4wd, all stock) that had some vibrations going on at around highway speeds.

Took out front driveshaft and the vibrations went away.
Bought a kit and redid the CV joint and u-joints. Put it back in and it's still vibrating. Also, the transfer case started to act up and wouldnt kick it out of part time, had to put it in R a couple of times and it finally jumped back into 2wd. Has some binding when this was happening.

Not sure what to do now.

Done so far:
– CV joint and front shaft U-joints
– New Ujoints at axle ends
– Balanced tires
– New ball joints

Issues that might have something to do with it:
– Stock leaf springs are done for, have to get new ones. Sits about 2 inches too low in the rear (center over tire)
– Front axle, pinion yoke has some rotational play with a clunk.
– Rear driveshaft has all stock ujoints.

Any help is appreciated,
Hank

sycoglitch

There's one of two things that's the issue. Imbalanced front shaft. Or your front diff is in need of rebuild. Pinion end.

Have you opened the diff up yet and inspected. Done some noggin poking. You already found half your answers. Front DS out, vibes gone

NM-XJ

Could you clarify, sycoglitch?

Why would it be the pinon end of front diff if it goes away when the front DS is out? All the stuff in the diff is always turning..with or without front DS.

sycoglitch

It was said that the pinion has movement. Should have any rotational movement really, just a slight bit. Yes its always turning but when you have a rotational mass connected to it, it was enhance it. But I also said to make sure the DS balanced.

Jooman07

X2. I'd take it to a driveline shop and have them check the balance. Are both ends of the DS in the same orientation? Not one side of the yoke horizontal and the other vertical?

rgr4475

I har some vibrations at highway speeds and it ended up being a bad motor mount. Replaced those and the trans mount and that took care of it. Just a thought. Not sure if you inspected them or not. My driver's side mount, the rubber was visibly cracked.

McHank

So, if it's the pinion, then I'm in for a front diff rebuild or looking for a new front axle?

How do you mean same orientation?

Could be, but I think this is driveline related since the vibs went away after taking the front driveshaft out.

sycoglitch

Did you open the front diff yet and do some noggin pokin. Grab some 75-90 diff fluid. Its like 1.2 liters iirc, gotta google check that, and some rtv or a lube locker gasket. Take some time. Open her and Inspect for unusual wear. Metal shavings, et .

McHank

Haven't opened it up yet, will do tomorrow.

Jooman07

The yokes need to be in the same orientation.




If the t case side is vertical like this then the pinion side needs to be in this way as well.




You can separate them and if you don't put the halves back in the same way then that can cause vibe and balance issues.

McHank

Ok, I see. But that would only happen if I separated the ds halves?

Here's a pic of the ds after ujoint install:

Jooman07

Yeah that looks like it isn't the same. See how the clips on the bearing caps are in the same orientation on the pic I posted? It needs to be like that I'm pretty sure. Someone before may have separated the halves and not put it back like it was supposed to be.

Jooman07

If it is in the right orientation, who knows, it may be bent.

McHank

True, but I hope not. Will recheck the ds to see if something looks wrong.

sycoglitch

Either get a friend to lend you his shaft or take that one to a driveline shop and have them check for balance. They can also Check for alignment of it too, as just previously stated. Most shops should put it on the balancer and Check for free or check and give a quote to fix.